English for Specific Purposes involves a lot more than special vocabulary. Many English language teachers are called upon to teach in specific occupational settings where employees need the language for their work. On the next page, I have listed some specialist English dictionaries which provide useful material for teachers and learners of English for Specific Purposes. However, this is reference material rather than lesson materials.
Teachers who take up posts where a lot of time is spent offering specialist occupational or academic varieties of English, need to go beyond words and phrases.
It is perfectly rational for teachers preparing for ESP posts to buy reference dictionaries and word books on areas of specialist English. However, lexis is just a single level of linguistic analysis and not necessarily the most useful one. When I took up English teaching posts in company settings (steelworks in Sweden and electronics factory in Spain), I found that my learners knew the English words for almost every term relevant to their roles in the steel and electronics industries already.
Word-level English vocabulary may have been lacking for me, but not for people working in these specialist fields. What they wanted from me was practice in
Depending on specific fields, certain structural patterns will occur more frequently and take on different meanings than encountered in general English. For example, the verb tense in "this machine will print at 10 pages per minute" denotes performance or capacity at any time. "Will", in this context, has nothing to do with 'future time'.
It can be helpful to use a model of linguistic analysis (a step-by-step set of instructions as to what to look at!) to check
advances in the description of special registers of English (occupational / social / academic), followed the
publication of David Crystal & Derek Davy's Investigating English Style in
1969. Instead of confining analysis to the vocabulary alone, Crystal & Davy's model
encouraged investigation into the features of special registers or varieties of English at
every level of linguistic description. Briefly [so as not to lose sight of functional
criteria], these levels include
The first step of the analysis -  Graphetics and graphology - concerns text and layout. Given 'the language of politics' or 'the language of advertising' as examples of specific varieties of English, fonts and type face are likely to be relevant to the message you would want to convey if you were preparing a company brochure or a political party manifesto
Clearly, there are very close ties between structural analysis and functional analysis of special varieties of English.
My recommended starting point for teaching English for Specific Purposes is to
consider the functions of the specific language variety. This may be difficult to do until
you really get to know your learners and their duties, but there is quite a lot of
literature now on how particular varieties of English work. An appreciation of the
function of occupational registers, will make linguistic description of syntax, lexis and
phonological features much easier, because you will be able to bear in mind why
particular constructions, collocations and literary devices are being used.
Teaching special English is much more interesting than word-level vocabulary study; in any case, good vocabulary practice materials, as exemplified by books in the English Vocabulary in Use series, go beyond the role of simple reference dictionaries by marking out functional territory and supplying a framework for language use.
Establish the function of the special variety of English that you are attempting to teach - your learners will know it already!
Functionally, the languages of politics and advertising share a judicial quality. Judgement forms a part of several professional registers including the language of law (guilty or innocent) and religion (heaven and hell; wrong and right). Politicians are constantly striving to value their own party with a plus and their rival's party with a minus; advertisers are playing a very similar game with competing products. This leads to several different types of claims. On the positive side, we have:
Already another linguistic level of analysis is revealing itself:  syntax. The language of politicians and advertisers shares many conditional forms. Sentence length may be shorter than that of philosophers, because people in marketing know that the audience will switch off if you go on for too long. The political "sound byte" has replaced the more philosophical oratory of speakers like Michael Foot, whose 1983 Political Party Election Manifesto was unkindly labelled "the longest suicide note in political history". Similarly, television advertisments are slick "sound bytes" and modern politicians and advertisers have a tendency to speak in slogans. I doubt that this will change, even though there is now a lot of adverse reaction to what has come to be known as "spin".
Sound bytes and slogans influence both the phonology and syntax of the language of advertisers and politicians. Sound bytes are slick, so lists of what is good or bad should contain no more than three items; moreover, a sound byte should inplant itself in the listener's aural memory, so English phonology comes into play through:
Belief systems and appeals to assumed "common values"
Associated with the claims of achievements, promises and party or company philosophy are a set of appeals to common values. These appeals include:
The language used to illustrate political appeals promises a lot of fun when we come to examine  the lexical level of this special variety of English. The lexical features of political discourse go beyond what you will find documented in a reference dictionary of government and politics.
Both political-speak and advertising are in fact noted for the frequency of imagery and metaphor as well as containing an abundance of pretentious diction and meaningless words. George Orwell referred to the language of politics as "a catalogue of swindles and perversions". We are all familiar with vaguely defined noun phrases (usually applied to the rich and greedy states) such as "freedom, tolerance and democracy", "a force for good in the world". Verbal phrases used in avoidance of clear thought include dying metaphors such as "toe the line"; "play into the hands of" and "have no axe to grind". False limbs used for similar avoidance include: "give rise to", "play a leading part in"; "make contact with"; "take effect". Another false limb consists in constructions of the "not un-" formation, which are used to give banal statements the appearance of profundity. A variation of this double negative can be found in a article entitled: "Britain's role in the world", written by Tony Blair in February 2003. Political-speak contains most swindles and perversions when politicians are fighting their way out of a corner. Criticized for being George Bush's poodle, Tony Blair tells labour party supporters: "I didn't hesitate to disagree at times, by the way, with Bill Clinton when he was President".
An analysis of metaphor in the language of politics can be found in Treuhaft's humorous study: An Investigation into current L (or Left-wing) Usage; which appears as a postscript to Jessica Mitford's account of her involvement with the American Communist Party in A Fine Old Conflict. This work dates from 1977, but the same old metaphors are uttered today by politicians who by no means regard themselves as communists. Four of Treuhaft's thirteen sections [I have filled out the illustrations] are as follows:
More functional analysis
stemming from the importance of "product discrimination" in the use of these registers:
Returning to the main function of political discourse or advertising-speak, positive claims are needed for "group cement", but equally a set of negative claims are needed for use against your opponent or rival for "product differentiation". These include:
Closely associated with product differentiation are the categories of dramatization and individuality. These are the categories which enable fairly easy identification of the political authorship of phrases such as: "mass unemployment" [Michael Foot of Margaret Thatcher's government] , "armed forces of the Crown", "present, steadfast progress towards recovery" [Margaret Thatcher of her own government] or "reputation for prudence and sound economic management" [Gordon Brown of his own stewardship]. The more colourful the stamp (within reason!), the better the level of product differentiation.
Dramatization results in lexical items such as: "watershed", "wasteland", "wreckers", "extremists", "scandal", "obscenity" as well as collocations such as "fateful day", "eleventh hour", "rigid controls". Verbs phrases can be just as rich in imagery as noun phrases and include: "accelerated into decline", "inflamed (the bitterness)", "illuminate (the corridors)", "piling up (new crises)", "distorted (by extremes)", "bumping (along the bottom)", "lurch into (extreme..)", "rob", "blighted", "aborting", "dividing", "fuelling (hopelessness and crime)", "tackling (difficult issues)"; "turning our back (on Europe)"; "pressing (governments, leaders, presidents and other important people)", "taking the lead (on the issue of weapons of mass destruction)" i.e. bombing Iraq.
The reference dictionaries listed on the next page, are what they say they are. A dictionary of politics or terms used in the advertising industry is useful if you operate in those spheres, but in order to get any real insight into an occupational or social variety of English you have to study the functions for which it is used. Single items of vocabulary and other lexical items [ such as collocations and phrasal verbs ] only represent one level of linguistic analysis. Larger units such as syntax and topic structure of text need just as much attention and smaller units such as alliteration (at the level of phonetics or phonology) can make a significant contribution to the meaning of language. Reference dictionaries tend to be formal works and I would like to see a dictionary of politics which did justice to the use of metaphor, insult and exaggeration. Most varieties of language (even legal English!) contain categories of use where lexis is fun and you may need to make creative use of a concordancer and a broadly representative corpus in order to uncover the areas where words are used creatively rather than with precision. Lawyers for the defence and prosecution are involved as part of their work in a game of product discrimination. It would be a weak barrister or judge who did not know how to use a powerful image.